A Simulation of the Cape Breton Snow Crab, Chionoecetes opilio, Fishery for Testing the Robustness of the Leslie Method

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Mohn, R. K., Elner, R. W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1987
• Subjects: Chionoecetes opilio; Snow crab
• Online Access: http://dx.doi.org/10.1139/f87-245; http://www.nrcresearchpress.com/doi/pdf/10.1139/f87-245

The principal tool for evaluating biomass and, hence, exploitation rate for Atlantic snow crab, Chionoecetes opilio, has been the Leslie method which is based on commercial catch rate and cumulative catch through the fishing season. The method assumes a dosed, homogeneous stock. However, a snow crab stock is often not closed because recruitment can occur during the fishing season as crabs molt into legal size. Also, stocks are not homogeneous and spatial heterogeneity causes fishermen to combine fishing and searching activities. A dynamic simulation of fishing/searching on a heterogeneous sessile stock with within-season recruitment was developed, based on the Cape Breton fishery, to assess the robustness of the Leslie method. In the modelled system, the violations of the assumptions caused by recruitment were shown not to be serious; but those due to the fishing/searching on a heterogeneous stock caused the Leslie method to underestimate initial biomass. Furthermore, the concepts of initial biomass and exploitation rate are seen to be inadequate for heterogeneous, recruiting stocks.